Punched fin elements for heat exchangers



March 24, 1953 atented Mar. 24, 1953 BUNCHE'DL FIN ELEMENTS FOR HEAT EXCHANGERS;

William E. Hammond and PerHilrnerl` Karlsson... Wellsville, N. Y., assignors tof'lhe Air` Preheaten, Corporation, New York, N. Y.

Application December 15, 1948, Serial No. 65,365

1 Claim.

The present invention relates to heat exchange Iapparatus and particularly to improved heat exchange components comprising members that form passage walls and are equipped with extended surface in the nature oi' fins, together with improved methods for making the same.

VIn heat exchangers used in transferring heat between gaseous media a familiar type embodies parallel metallic plates spaced to form uid passages with alternate passages employed for the heating fluid and the intermediate passages for the fluid that is to absorb the heat. To improve the heat transmission in such exchangers extended surface is frequently provided in the form of ns projecting from the walls through "which the heat is to be transferred. This invention is directed to providing such passage walls with extended surface presenting a multiplicity of pin-like ns in the path of the heating gas and will be best understood upon consideration of the following detailed description of illustrative embodiments of the invention when read in conjunction with the accompanying drawings in which:

Figure 1 is a fragmentary perspective view of a plate from which is formed a wall component provided with a multiplicity of attached heat exchange fins;

Figure 2 is a sectional end View of the plate after the punched out tab-like ns have been raised from the plate surface;

Figure 3 is a perspective view of a heat exchanger showing the several passages in which the flnned surface is applied;

Figure 4 illustrates another arrangement similar to Figure 3.

Heat exchangers of the type to which the invention is directed are made up of parallel plates forming adjacent iiuid passages divided into groups with alternate passages providing flow paths for the heating gas while the intermediate passages are traversed by air or other fluid that is to be heated. A portion of such a heat exchanger is illustrated in Fig. 3 wherein the parallel metallic plates form a series of fluid passages I2 and I4 for the two fluids. such as air and gas, between which heat is to be exchanged. The walls oi' the heat exchange passages are provided with a myriad of pin-like tins IB projecting from the plate walls into the area traversed by the fluids, pin-fins being shown in both sets o-f passages in Fig. 3 although channel-like n elements may be provided in one set of passages. T'he finned surface embodied in the heat exchanger illustrated in Fig. 3 is formed by punching a rectangular metallic plate 20 (Fig. 1) with a plurality of rows of closely spaced openings 22 and retaining the metal from the area of the openings attached to the plate along one edge of the opening and bending these tabs from the surface of the plate so as to form fins I6 projecting preferably normally from the plate surface. In constructing a heat exchanger from the finned plates shown in Figs. 1 and 2, these plates, after the punchings have been made and the tabs erected, are assembled so that between alternate pairs of plates 20 a solid or imperforate metal plate 24 of equal area is interposed and brazed or welded so as to seal the openings 22 that remain upon punching the fins I 6 from the plate metal, the plates 20 being disposed so that fins I6 project from opposite walls into the fluid passages I 2 o-r I4. In Fig. 3 the fins I6, ISA on opposite walls of passage I2 are staggered. Instead of imperforate plates 24 of the area of the passage wall-forming plates 2U a series of strips of metal might be used; alternatively, channels 26 may be provided in the intermediate or air passages as shown in Figure 4 and so located as to extend along the axis of the rows of openings 22 in the plates 20 in order to seal these openings against cross-flow of uids between the air and gas passages I2 and I4, respectively. To attain a closer spacing of the lns I6 two of the plates 20A, 20B may be used for each of the opposing walls of a passage with the two plates stacked so the tab-like fins ISB on one plate 20B project through the openings 22A on the other plate 20A and extend into the gas stream in close juxtaposition to the fins ISA and IBC raised from the plate 26A itself.

By using two of the nned plates back to back ns may be provided in both of the adjacent passages separated by the wall constituted by the plates to close the apertures 22 left by punching the fins, an intermediate plate may be interposed between the plates mounted back to back.

With nned plates mounted back to back and intermediate plates between them, a construction is provided which has the additional advantage of permitting the long axis of the fins to run in the same direction in adjacent passages or with their long dimension at right angles to each other in adjacent passages so that either a parallel flow or counterow heat exchanger may readily be constructed.

What is claimed is:

A heat exchange iluid passage comprising first and second spaced plates each provided with a multiplicity of parallel rows of closely spaced pinlike ns struck from the plate material and each bent substantially normally to its surface along an edge of the perforation from which it is struck and extending between said plates; one or more imperforate members contacting the opposite side of each nned plate to close the perforations remaining on raising the fins from the plate surface; and an additional finned plate between the rst plate and the imperforate member with the pin-like ns of the said additional plate projecting through the perforations in the rst plate contiguous to the ns thereof to provide a closer spaced relation of fins in said passage.

WILLIAM E. HAMMOND. PER. HILMER KARLSSON.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,313,730 Pease Aug. 19, 1919 1,775,819 Fischer et al. Sept. 16, 1930 2,327,757 Barrett Aug. 24, 1943 2,471,960 Johnson May 31, 1949 2,507,862 Mead May 16, 1950 

